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EWG's Tap Water Database — 2019 UPDATE

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Chlorate

City of Sugar Land

Chlorate forms in drinking water as a byproduct of disinfection. Chlorate impairs thyroid function, making chlorate exposure most harmful during pregnancy and childhood. Read More.

In 2002, California scientists proposed an advisory value, called an action level, for chlorate at 200 parts per billion. Between 2013 and 2015, the EPA collected data through the Unregulated Contaminant Monitoring Rule program and found that over 15 percent of water tests from 38 percent of utilities had chlorate levels above a health-protective concentration, which federal scientists defined as 210 parts per billion, nearly equivalent to the California advisory value.

Click here to read more about disinfection byproducts.

 

22

Samples

0

Samples exceeding legal limit (MCL)

3

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012N/A00N/A
201337.5 ppb223ND - 330.0 ppb
2014N/A00N/A
2015N/A00N/A
2016N/A00N/A
2017N/A00N/A

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 210 ppb

The EWG Health Guideline of 210 ppb for chlorate was defined by the Environmental Protection Agency as a benchmark for testing under the Unregulated Contaminant Monitoring Rule program. This health guideline protects against hormone disruption.

ppb = parts per billion

All test results

Date Lab ID Result
2013-01-22201301240319AMND
2013-01-22201301240159AMND
2013-01-22201301240191AMND
2013-01-22201301240222AMND
2013-01-22201301240183AMND
2013-01-22201301240189AMND
2013-01-22201301240285AM256.0 ppb
2013-01-22201301240216AMND
2013-01-22201301240266AMND
2013-01-22201301240251AMND
2013-01-23201301240187AMND
2013-06-18201306190368AMND
2013-06-18201306190355AMND
2013-06-18201306190358AM240.0 ppb
2013-06-18201306190346AMND
2013-06-18201306190324AMND
2013-06-18201306190360AMND
2013-07-01201307020418AMND
2013-07-01201307020424AMND
2013-07-17201307180591AMND
2013-07-17201307180589AMND
2013-07-17201307180593AM330.0 ppb